Light emitting device emitting UV-C radiation at different wavelengths upward and downward

Abstract

In one embodiment, a light emitting device comprises one or more first light sources emitting UV-C light downward to irradiate the environment below the light emitting device (such as air and the floor and other surfaces). In another embodiment, the light emitting device comprises one or more second light sources emitting UV-C light of a different peak wavelength than the first light sources oriented to emit light upward to irradiate the environment above the light emitting device (such as air, the ceiling, and other surfaces). In one embodiment, one or more first light sources and the one or more second light sources emit light at different, independent duty cycles.

What is claimed is: 
     
         1 . A light emitting device comprising:
 one or more first light sources emitting a first radiant flux with a peak wavelength within a wavelength range of 220 nanometers and 225 nanometers; and   one or more second light sources emitting a second radiant flux with a peak wavelength of 254 nanometers,   wherein the first radiant flux is directed downward, and the second radiant flux is directed upward when the light emitting device is suspended or mounted in an environment.   
     
     
         2 . The light emitting device of  claim 1  wherein the first radiant flux has a peak wavelength of 222 nanometers. 
     
     
         3 . The light emitting device of  claim 2  wherein the one or more first light sources comprise an excimer lamp. 
     
     
         4 . The light emitting device of  claim 2  wherein the one or more second light sources comprise a mercury vapor lamp. 
     
     
         5 . The light emitting device of  claim 1  further comprising at least one light detector sensitive to light within a wavelength range of 100 nanometers to 280 nanometers. 
     
     
         6 . The light emitting device of  claim 3  wherein the at least one light detector includes a spot meter. 
     
     
         7 . The light emitting device of  claim 3  wherein the at least one light detector includes an imager. 
     
     
         8 . The light emitting device of  claim 1  further comprising at least one motion sensor or occupancy sensor. 
     
     
         9 . The light emitting device of  claim 1  wherein the one or more first light sources and the one or more second light sources emit light at different, independent duty cycles. 
     
     
         10 . The light emitting device of  claim 1  wherein the light emitting device further comprises an indicator light that emits visible light when the one or more first light sources has reached a time threshold, the time threshold is a threshold less than 30% of an expected lifetime remaining for the one or more first light sources. 
     
     
         11 . The light emitting device of  claim 1  wherein the first radiant flux from the one or more first light sources divided by the second radiant flux from the one or more second light sources when the one or more first light sources and the one or more second light sources are emitting light at a maximum power allowed by the light emitting device is less than 1. 
     
     
         12 . The light emitting device of  claim 1  further comprising a fan that directs air from the environment across the second radiant flux. 
     
     
         13 . A light emitting device comprising:
 one or more first light sources emitting a first radiant flux with a peak wavelength of 222 nanometers at a first duty cycle; and   one or more second light sources emitting a second radiant flux with a peak wavelength of 254 nanometers at a second duty cycle different than the first duty cycle, wherein the first radiant flux is directed downward, and the second radiant flux is directed upward when the light emitting device is suspended or mounted in an environment.   
     
     
         14 . The light emitting device of  claim 13  wherein the light emitting device further comprises at least one motion sensor or occupancy sensor and an indicator light that emits visible light when the one or more first light sources has reached a time threshold, the time threshold is a threshold less than 30% of an expected lifetime remaining for the one or more first light sources. 
     
     
         15 . The light emitting device of  claim 13  wherein the first radiant flux from the one or more first light sources divided by the second radiant flux from the one or more second light sources when the one or more first light sources and the one or more second light sources are emitting light at a maximum power allowed by the light emitting device is less than 1. 
     
     
         16 . The light emitting device of  claim 13  further comprising a fan that directs air from the environment across the second radiant flux. 
     
     
         17 . The light emitting device of  claim 13  further comprising at least one motion sensor or occupancy sensor and at least one light detector sensitive to light within a wavelength range of 100 nanometers to 280 nanometers. 
     
     
         18 . A method of reducing a pathogenic bioburden in an environment, the method comprising:
 suspending or mounting a light emitting device in an environment;   emitting from one or more first light sources a first radiant flux with a peak wavelength within a range of 220 nanometers and 225 nanometers downward into the environment; and   emitting from one or more second light sources a second radiant flux with a peak wavelength of 254 nanometers upward into the environment.   
     
     
         19 . The method of  claim 18  wherein the first radiant flux from the one or more first light sources divided by the second radiant flux from the one or more second light sources when the one or more first light sources and the one or more second light sources are emitting light at a maximum power allowed by the light emitting device is less than 1. 
     
     
         20 . The method of  claim 19  wherein the one or more first light sources and the one or more second light sources emit light at different duty cycles.